/*
 * Copyright (c) 2011-2012 Alexander Dubu
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * o  Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * o  Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * o  Neither the name Axil nor the names of its contributors may be used to
 *    endorse or promote products derived from this software without specific
 *    prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
package axil.stdlib.core.function;

import axil.api.AxilObject;
import axil.api.AxilType;
import axil.api.extend.Environment;
import axil.api.extend.Function;
import axil.api.extend.Parameters;
import axil.api.extend.Source;
import axil.stdlib.core.type.Bool;

import static axil.framework.Functions.*;


/**
 * Tell if an object of the given type can be created without error from the
 * string representation of that type. For example:
 *
 * 		if(new?(type("date"), "2012/01/01"),
 * 			then(print("good")),
 * 			else(print("bad")))
 *
 * Note that a type that is not accessible, not defined, or for which instances
 * cannot be created will also return a false value.
 */
public class NewQ implements Function {
	/**
	 * Execute this function with the given arguments. The Axil compiler will
	 * ensure that the number of arguments passed to the function are valid.
	 * If this function fails during execution for any reason, then an exception
	 * is thrown.
	 *
	 * @param env
	 * 	The environment in which the function is being invoked. The environment
	 * 	is never null.
	 *
	 * @param params
	 * 	The parameters to the function, which can be any Axil object. The values
	 * 	given are never null but may be the nil object (Axil.NIL).
	 *
	 * @params source
	 * 	The source which is the original of the code invoking this function.
	 *
	 * @return
	 * 	Returns any Axil object, but not null. Use the Axil.NIL object for a
	 * 	null value.
	 */
	public AxilObject eval(Environment env, Parameters params, Source source) {
		AxilObject a = params.a();
		AxilType type;
		if (a instanceof AxilType) {
			type = (AxilType)a;
		} else {
			final String ident = str(params.a());
			type = env.configuration().type(ident);
			if (type == null) {
				throw error(axil(), "unknown-type", nv("type", ident));
			}
		}
		if (type.creatable()) {
			AxilObject object = type.parse(params.b().toString());
			return bool(object != null);
		}
		return Bool.FALSE;
	}
}
